This invention relates generally to the subcutaneous, intracutaneous, intramuscular or deeper injection of medications and the like, and, more specifically, to an apparatus for use with disposable syringes, which provides a convenient handling mechanism permitting easy, one-handed, two-way operation of the syringe.
In making subcutaneous injections of certain medications, a grave hazard exists from the possibility that the medication can be unintentionally injected directly into the blood vessel. When a medication and/or biological substance is injected directly into the blood stream, a generalized reaction can occur due to the extent and rapidity of the distribution of the medication and the rapidity of the patient's reaction. In order to eliminate, or at least minimize, this hazard, it is a recommended procedure that after inserting a syringe needle to make an injection, the plunger of the syringe is withdrawn a small amount to create a negative pressure within the injection chamber. If the needle point opening of the syringe has been accidentally placed within the lumen of a blood vessel, the negative pressure within the injection chamber would draw blood immediately into the syringe and, thus, provide an immediate signal to terminate the procedure before the medication is injected. If the negative pressure yields no blood return, then it may be presumed that the needle point opening is positioned outside any blood vessel and the medication may be safely injected into the subcutaneous or intramuscular space where the open end of the needle point has been placed. Because it is an awkward procedure to first withdraw the plunger before injecting the medication, the technician, nurse or physician will frequently omit this initial safety maneuver and will instead directly inject the medication.
It has been known in the art to provide an integral thumb ring on the exposed end of the plunger of a syringe to permit control of the movement of the plunger in both the injecting and retracting or aspirating directions. Such structure would facilitate withdrawl after the needle has been inserted without having to change the grip on the syringe. However, the inclusion of a thumb ring on each syringe adds to the manufacturing cost of a syringe, a factor which is particularly important with respect to disposable syringes. Such disposable syringes can be manufactured in sterile conditions and packaged in sterile containers prior to use, and can even be prefilled with a medicinal fluid at the factory. The provision of a ring integral with the plunger on each syringe would significantly add to the cost of production, as well as adding to the sizes of packages needed to ship and store these syringes.
Previous attempts have been made to provide detachable devices for controlling movement of syringe plungers. Many simply include rings attachable to the plunger head. See, for example, U.S. Pat. Nos. 4,217,896; 4,324,241; and 4,351,334. None, however, has been entirely satisfactory.
Accordingly, there has been a need for a novel injection assisting apparatus which provides a convenient handling mechanism permitting easy, one-handed, two-way operation (aspiration and injection) of a syringe. Additionally, there exists a need for such an apparatus which is capable of accommodating syringes of constant diameter/varying lengths, or syringes of constant length/varying diameters. Further, an injection assisting apparatus is needed which supports the syringe barrel and plunger in a fixed aligned relationship, and which can be constructed economically of material readily sterilized. It would be preferable, moreover, to provide such an injection assisting apparatus with finger and thumb rings oriented to account for the natural angular relationship between the thumb and the index and middle fingers. The present invention fulfills these needs and provides other related advantages.